Main Difference – Hydrochloric Acid vs Muriatic Acid
An acid is a chemical compound having characteristic properties such as turning blue litmus red, neutralizing alkali solutions and corrosiveness. Hydrochloric acid is a strong acid compared to other acids. People often confuse Muriatic acid with hydrochloric acid, assuming that both are the same; however, there is a slight difference between hydrochloric acid and Muriatic acid. The main difference between hydrochloric acid and Muriatic acid is that hydrochloric acid is composed of only HCl molecules whereas Muriatic acid is composed of impurities along with HCl molecules.
Key Areas Covered
1. What is Hydrochloric Acid
– Definition, Properties, Uses
2. What is Muriatic Acid
– Definition, Properties, Uses
3. What is the difference between Hydrochloric Acid and Muriatic Acid
– Comparison of Key Differences
Key Terms: Acid Dissociation Constant, Baume Rating, Chemical Formula, Hydrochloric Acid, Iron, Muriatic Acid, Steel, Strong Acid
What is Hydrochloric Acid
Hydrochloric acid is a strong acid with the chemical formula HCl. It is very corrosive in its concentrated form. Hydrochloric acid is a colorless solution prepared by dissolving hydrogen chloride (HCl) in water. The molar mass of Hydrochloric Acid is about 3605 g/mol.
Hydrochloric Acid is a monoprotic acid. That means hydrochloric acid releases one proton (H+) per molecule in its aqueous solution. Therefore, hydrochloric acid fully dissociates in water. Thus, it has a high value for acid dissociation constant (Ka).
Hydrochloric acid has many applications in laboratory scale and industrial scale. One such industrial scale application is refining metals. This acid is used in refining metal because most of the metals are easily dissolved in it.
Figure 1: The Lewis Structure of Hydrochloric Acid
Another important application of hydrochloric acid is pickling of steel, that is, the removal of rust (iron oxide) from iron or steel. The reaction that occurs here is given below.
Fe2O3 + Fe + 6HCl → 3FeCl3 + 3H2O
What is Muriatic Acid
The chemical formula of Muriatic acid is also HCl. Therefore, Muriatic acid is also known as hydrochloric acid. But unlike hydrochloric acid, Muriatic acid is a yellow colored solution since it contains impurities. The yellow color is due to the presence of trace amounts of iron.
Muriatic acid is prepared by distilling hydrochloric acid and salt (containing chloride ion). This preparation method causes the presence of impurities in Muriatic acid. However, these impurities do not affect the applications of Muriatic acid.
Baume rating is a scale used to measure the density of a liquid. According to this scale, Muriatic acid has a lower Baume rating value compared to hydrochloric acid.
Uses of Muriatic acid includes use as a cleaning agent for swimming pool water (for this application, pure hydrochloric acid is not needed. Therefore, Muriatic acid is a good choice) to adjust the pH to a proper value. Muriatic acid is also used to clean metal surfaces because the acid strength of Muriatic acid is relatively low and is not enough to dissolve a metal.
Figure 2: A Bottle of Muriatic Acid Solution
Difference Between Hydrochloric Acid and Muriatic Acid
Definition
Hydrochloric Acid: Hydrochloric acid is a strong acid with the chemical formula HCl.
Muriatic Acid: Muriatic acid is HCl with impurities.
Color
Hydrochloric Acid: Hydrochloric acid is colorless.
Muriatic Acid: Muriatic Acid is slightly yellow colored.
Composition
Hydrochloric Acid: Hydrochloric acid is composed only of HCl molecules.
Muriatic Acid: Muriatic Acid is composed of HCl along with other molecules such as H2SO4 and iron.
Purity
Hydrochloric Acid: Hydrochloric acid is a very pure solution.
Muriatic Acid: Muriatic Acid is less pure compared to hydrochloric acid.
Baume Rating
Hydrochloric Acid: Hydrochloric acid has relatively a high Baume rating value.
Muriatic Acid: Muriatic Acid has relatively a low Baume rating value.
Applications
Hydrochloric Acid: Hydrochloric acid is used where a strong acid condition is needed; it is used mostly in laboratory scale.
Muriatic Acid: Muriatic Acid is used where a mild acid condition is needed and is used mostly in industrial scale and for cleaning purposes.
Conclusion
When handling acids, care should be taken even though they are low concentrated acids or weak acids. This is because almost every acid causes skin injuries due to their corrosive nature. Hydrochloric acid is a good example for a strong acid. The main difference between hydrochloric acid and Muriatic acid is that hydrochloric acid is composed of only HCl molecules whereas Muriatic acid is composed of impurities along with HCl molecules.
References:
1. “Hydrochloric acid.” Hydrochloric acid – New World Encyclopedia. N.p., n.d. Web. Available here. 30 June 2017.
2. Helmenstine, Anne Marie. “Quick Facts about Muriatic Acid.” ThoughtCo. N.p., n.d. Web. Available here. 30 June 2017.
Image Courtesy:
1. “Elektronenformel Punkte HCl” By Apostoloff – Own work (Public Domain) via Commons Wikimedia
2. “SAFER Muriatic Acid!” by Morgan Davis (CC BY 2.0) via Flickr
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